1. Field of the Invention
The present invention relates to a liquid crystal display device and, more particularly to a liquid crystal display device of a matrix display type.
2. Description of the Prior Art
In recent years, with the development of information processing devices such as computers, emphasis has been placed on the role to be filled by display devices as information communicating means. The conventional typical display device was a CRT (Cathode Ray Tube). However, a liquid crystal display device is now preferred in view of the advantage of minimizing the construction and decreasing the power consumption. Further, there is a keen need for a liquid crystal display device of large screen area, and at the same time, of large capacity.
For the materialization of such a device, attention is now being paid to a liquid crystal display device utilizing ferroelectric liquid crystals. Typically, chiral smectic liquid crystals are used for ferroelectric liquid crystals. Molecules of ferroelectric liquid crystals are aligned in a helical structure under normal conditions. However, it is known that if a thickness of liquid crystal layer smaller than a helical pitch of the helical array is selected, two stable orientations can be obtained in the ferroelectric liquid crystals. These two orientations mean that, when a positive electric field, i.e., positive voltage is applied, the liquid crystal molecules are oriented in a first state of orientation, in contrast, when a negative electric field, i.e., negative voltage is applied, the liquid crystal molecules are oriented in a second state of orientation. It is also known that transition from the first state of orientation to the second one occurs extremely quickly.
In a liquid crystal display device utilizing the aforesaid ferroelectric liquid crystals, the liquid crystal molecules should be uniformly oriented in the liquid crystal layer to obtain good display properties. In practice, however, it is very difficult to obtain such a uniform orientation because disclination, i.e., various orientations of the liquid crystal molecules occurring in the same layer, or the like occur. In particular, the aforesaid two stable orientations exist in the areas other than the pixel areas and to which voltage is not applied. Consequently, bright areas and dark areas are intermingled in the display screen of the liquid crystal display device, thereby significantly deteriorating the display quality of the device.
Further, when the liquid crystal display device is driven, voltage is applied to one end of each of electrodes. If resistance of an electrode is high, voltage at the other end of the electrode is significantly lowered. As a result, voltage applied to the liquid crystal layer becomes multiform, so that the display properties of the liquid crystal device is rendered multiform. To overcome these problems, Japanese Published Unexamined Patent Application No. 11911/1988 discloses a liquid crystal display device in which a conductive shading layer covers the spaces between electrodes while at the same time one end of the layer is in contact with one side of each of the electrodes. However, in order to prevent a short circuit between one electrode and another electrode adjacent thereto, such a device is required to be so devised that (1) a microscopic space is provided between the conductive shading layer and the adjacent electrode, or (2) an insulating film is provided therebetween. In the case of (1), it is not easy to provide such a microscopic space, and if the space is enlarged, shading effect becomes incomplete. As well, in the case of (2), problems may occur in insulating properties of the insulating film, besides manufacturing process of the device becomes complicated because steps of forming the insulating film and patterning thereof must be added to the usual process.